Question

Name each of the following alkanes.

Short answer

a. Pentane

b. 3 -ethyl- 2,5 -dimethythecane

c. 4-ethyl-5-isopropylotane

Step-by-step solution

Rules for naming alkanes

Rules for naming alkanes:

Find the longest continuous chain of carbon atoms, and use the name of this chain as the base name.

Number the longest chain so that the substituent’s get the smallest numbers.

Name the substituent groups attached to the longest chain as alkyl groups and determine their position.

Combine location and name of each substituent with the base name.

Pentane alkane

a. The longest continuous chain of carbon atoms has carbon atoms. Therefore, name of this alkane is pentane.

Hence, the above alkanes is pentane.

Hexane alkane

b. The longest continuous chain has 6 carbon atoms. The name of this alkane is hexane.

We have two methyl groups at positions 2 and 5, and one ethyl group at position 3. Hence the name of this alkane is 3 -ethyl-2,5-dimethylhexane.

Hence, the above alkanes is 3 -ethyl- 2,5 –dimethythecane.

Octane alkane

c.

The longest continuous chain has 8 carbon atoms. The name of the parent alkane is octane.

Octane has two substituents, ethyl, and isopropyl at positions 4 and 5.

Hence the name 4-ethyl-5-isopropyloctane.

Hence, the above alkanes is 4-ethyl-5-isopropylotane.